Resonance Raman spectroscopic studies are planned for a wide variety of heme protein and related molecules. Results to date demonstrate that the technique is highly sensitive and specific, and that it will be useful as a structural probe in solution. Molecules under study include hemoglobin, myoglobin, cytochrome c, cytochrome P450, peroxidase and vitamin B12. By studying these molecules, both in isolation and in their biological matrices, we hope to use resonance Raman spectroscopy to help elucidate the relationship between their structure and their biological function.